Prosthetic liner with proximal seal

ABSTRACT

Disclosed is a prosthesis suspension assembly, the assembly comprising: a prosthetic liner comprising a distal outer surface comprising a porous or continuously cavitated, compressible material and a proximal surface comprising an elastomeric material; and a suspension sleeve which seals against the proximal surface.

PRIORITY

This application is a non-provisional of U.S. provisional applicationSer. No. 61/034,323, filed on Mar. 6, 2008, which is herein incorporatedby reference.

BACKGROUND

During the 1980's, a means of suspending a prosthesis was developedwhich consisted of a docking means fabricated into an interface which,in turn, was rolled onto the distal portion of the wearer's residuallimb. The docking means engaged into the prosthesis, and the prosthesiswas thereby locked in position of attachment to the patient's limb.

Such a means of attachment became standard in the industry. However, ithad drawbacks which ultimately led to its supplantation by othermethods. One major drawback was the tendency of the residual limb topiston, or slip upwards and downwards in the interface upon ambulation.Over the years, it has been thought that pistoning occurred because onlythe distal portion of the limb was involved in the support of theprosthesis. The limited support resulted in a high degree of angular andtorsional stress at the interface of the socket/liner and the residuallimb. The pistoning, in combination with the sucking effect caused bythe interface, caused the limb to change in volume with ambulation. As aresult, the fit of the prosthesis changed with wear throughout the day.It was necessary for the wearer to make use of a thick prosthetic sockon the residual limb in an attempt to compensate for the limb's changein volume during use of the prosthesis and alleviate some of thediscomfort which was experienced as a result of pistoning. However, thesock added an inconvenient bulk to the already awkward task of wearing aprosthesis, as well as creating sanitary issues due to the collection ofsweat and dirt.

In the 1990's, suspension sleeves were used to create a seal between theresidual limb and the prosthesis. The suspension sleeve is an elastic orelastomeric tube which, when properly positioned, forms a seal whichencompasses 1) the proximal lip of the prosthesis socket, 2) the entireportion of the interface external to the socket, and 3) a portion of thewearer's thigh just above the proximal end of the interface. The sleeve,employed in its sealing capacity, is illustrated in FIG. 2. The sealcreated by the elastomeric sleeve is able to support a modest vacuum.The vacuum is typically in the range of from greater than about 2 inchesHg to about 14 inches Hg. One way valves embedded in the prosthesissocket/liner or pumps are often used to establish and maintain thevacuum.

The sealed socket limb junction largely eliminates the pistoningproblem. A layer of fabric or other porous or continuously cavitatedcompressible material such as, for example, a synthetic foam, overliesthe entire interface and occupies an area between the socket and theinterface, and serves to “wick” the vacuum to the entire volume occupiedthereby, yet it prevents the interface from coming into contact with thesocket, effectively establishing a volume over which a vacuum can besustained.

However, this method introduces new problems. The upper reaches of theseal extend onto the thigh of the wearer, essentially including the skinof the wearer in the partially evacuated volume. The skin directly underthe sleeve chafes from the elastic motion of the sleeve as the residuallimb compresses and decompresses with the ambulation cycle. Furthermore,bending at the knee causes the sleeve to bunch directly behind the kneeand on the back of the leg above the knee, and stretch tightly in theanalogous positions on the front of the residual limb. Such motion cancause blistering and subsequent infection and pain, even to the extentof requiring the wearer to forego the use of the prosthetic for periodsof time. Nevertheless, the sealing of the partially evacuated volume byextending the sleeve to the wearer's thigh, and the inclusion of thewearer's skin as a bounding surface to the partially evacuated volumehave persisted as part of the solution to the pistoning problems arisingfrom earlier designs.

A prosthetic liner system surmounting the foregoing problems associatedwith the thigh-sealing liner system, yet maintaining the effectivenessagainst pistoning demonstrated by the thigh-sealing liner system wouldrepresent an advance in the prosthetic liner industry.

Surprisingly, it has been found that when 1) the outer surface of only adistal portion of the interfacing layer is covered with a porous orcontinuously cavitated compressible material, 2) the proximal portion ofthe interfacing layer has a sealable, preferably elastomeric outersurface, and 3) the proximal portion of the sleeve extends to and sealsagainst the proximal portion of the liner; the pistoning is stillgreatly reduced, even though the seal does not extend up onto the thigh.

In one embodiment, the present invention comprises a prosthetic linercomprising a distal closed end; a proximal open end comprising aproximal edge; an inner surface; an outer surface; an elastomeric layer;and a layer of compressible porous or continuously cavitated material(“material” layer). The inner surface comprises the elastomeric layer;the outer surface comprises the material layer and the elastomericlayer, and the material layer overlays the elastomeric layer except fora continuous region of the outer surface comprising the proximal openend. At the material leading edge, the outer surface transitions fromfabric to a circumferentially continuous region comprising acircumferentially continuous sealable surface.

In another embodiment, the present invention further comprises aresidual limb comprising a distal end which is fittingly received intothe prosthetic liner.

In yet another embodiment, the present invention further comprises aprosthesis comprising a prosthetic socket into which the distal portionof the liner is fittingly received.

In yet another embodiment, the present invention further comprises asuspension sleeve comprising a proximal and distal portion, wherein thedistal portion seals against the prosthetic at a position more distalthan the socket edge, and the proximal portion of the sleeve sealsagainst the liner at a position not covered by the porous orcontinuously cavitated compressible material (i.e., against theelastomeric outer surface of the proximal portion of the liner).

In yet other embodiments, the prosthetic liner in the above embodimentsfurther comprises a pin in the distal end which engages a hole or cavityin the prosthesis, locking the prosthesis onto the residual limb. Inadditional embodiments, the pin comprises a one way valve which permitsexit of the air in the volume bounded by the interface, the socket andthe suspension sleeve (“interstitial volume”).

The present invention is effective over a range of liner lengths. Byliner length, it is meant the distance from the distal tip of the linerto the proximal edge of the proximal open end. Liner lengths in therange of from about 8 inches to about 30 inches are preferred, withlengths in the range of from about 12 to 24 inches more preferred. Ingeneral, it is desirable that the liner have a length such that, whenworn, it extends at least about 5 inches up onto the wearer's residuallimb as measured from the residual limb's most distal point.

The present invention makes use of the fitting parameters which arestandard in the art, and thus, a liner which would be correctly fittedfor the current thigh-seal method is generally correctly fitted for thepurposes of the present invention. However, liners which may beconsidered uncomfortably tight or snug for use with the currentthigh-seal method can, in some cases, be used comfortably with thesuspension system of the present invention.

The liner of the present invention comprises an inner surface and anouter surface. The inner surface faces the residual limb, and in theabsence of other lining materials, contacts or interfaces with thesurface of the residual limb. The inner surface is conveniently a layerof elastomeric material preferably of a type compatible with longperiods of dynamic wearer contact. Such materials are known in the artand may include the following polymers, as well as gels which comprisethem: polyurethanes; block copolymers such as styrene block copolymers,general non-limiting examples of which may include SEBS-, SEPS-, SEEPS-,SEEBS-, and other type styrene block copolymers. Further non-limitingexamples of styrene block copolymers which may be useful in the liner ofthe present invention include so called “controlled distributionpolymers,” such as, for example, those disclosed in U.S. Pat. No.7,226,484; U.S. Patent Application Publication No. 20070238835; and U.S.Patent Application Publication No. 20050008669. Other potentially usefulpolymers may include certain so-called “crystalline” polymers, such as,for example, polymers disclosed in U.S. Pat. Nos. 5,952,396; 6,420,475;6,148,830 and 6,148,830. The above list is non-limiting, and in general,the list of acceptable polymers and gels includes those known in the artto be useful for the fabrication of prosthetic liners. By the term“gel,” is meant a polymer which has, associated with it, through meansknown in the art such as absorption, mixing, or other, a plasticizer.Gels which do not have a tendency to delaminate from the material layerare preferred.

It should be noted that the benefits of the present invention may obtaineven if the material lay contains other components, such as other layersof flexible materials (even if not elastomeric) as long as the surfaceof the material layer against which the suspension sleeve seals,described infra, is capable of sustaining the required vacuum.

Another aspect of the present invention is a distal liner portionbearing or covered with a porous or continuously cavitated compressiblematerial. The covering does not extend to the proximal edge of theliner. In another embodiment, the fabric does not “reach” the proximaledge of the liner, meaning that all points of the leading edge of theporous or continuously cavitated compressible layer are at least 1centimeter away from all points on the proximal edge of the liner, andin other embodiments, at least 3, 5, 8 and 12 centimeters from allpoints on the proximal edge of the liner. In additional embodiments, theleading edge of the porous or continuously cavitated compressible layerand the proximal edge of the liner each lie in a plane, and in stillother embodiments, the planes are parallel to each other andperpendicular to the long axis of the liner.

The material layer overlies a distal portion of the interface orelastomeric layer. In one embodiment, the material layer is in the shapeof a liner which slips over the distal end of the material layer. Inother embodiments, the material layer is bonded to the elastomericlayer. Included within, but not limiting the meaning of “bonded” isfabric that is glued, molded, dipped, affixed, adhered, or otherwiseimmobilized upon the surface of the elastomeric layer.

It should be noted that the material layer can be integral to theinterface layer, such as where the connection between the layers is aresult of melting or other processes such as chemical processes, or thegel interface is superficially processed to create a material layer fromthe gel, such as, for non-limiting example, chemically or thermallytreating the upper surface of the gel to cause the upper surface to forma foam.

The liner interfacing layer (“interface”) can be of a wide range ofthicknesses. In preferred embodiments, the interface has a thickness inthe range of from about 1 millimeter to 6 millimeters, or even thickeror thinner, with a more preferred thickness in the range of from about 2to about 4 millimeters. In general, it is not necessary for thethickness of the interface to be uniform throughout in order to obtainthe benefits of the present invention. The present invention can be usedon liners having thickness profiles which are nonuniform orextraordinarily thick or thin, such as profiles reflecting a materiallayer having a strategic distribution of extra cushioning or support,such as may be required for therapeutic purposes. Furthermore, theinterface layer can comprise additional layers of uniform or non uniformthickness, such as may be utilized to support or cushion certain regionsof the interface. In general, the term “interface” includes anelastomeric component which, optionally, comprises multiple layers ofelastomeric materials adhered together.

It is, however, strongly preferred that the face of the proximal portionof the interface intended to contact the inner surface of the intendedsuspension sleeve be of such a quality that a seal is formed between theinterface and the suspension sleeve which can sustain a moderate vacuumin the range of from about 2 inches Hg to about 14 inches Hg for longenough to enable the wearer to experience the benefits of the inventionfor significant periods of time, such as, for example at least about 0.5hrs, and more preferably, at least about 1, 2 or 3 hours.

In yet another embodiment the seal, when formed from an assemblycomprising a liner, a prosthetic socket and a sleeve, as well as aone-way valve permitting the exit of gas trapped in the material-filledspace between the interface, the liner and the sleeve, can sustain avacuum in the foregoing range for at least 10 or 20 minutes, andpreferably for at least 30, 40 50 or 60 minutes of ambulatory motion. Itshould be noted that because one-way valves may vary in efficiency, theability of the assembly to meet the foregoing time standards is aproperty not of the seal itself, but of the seal/valve combination.

As noted above, the liner also comprises a porous or continuouslycavitated compressible material or “material.” By “porous” is meant amaterial comprising interconnected cavities which vent to the surface ofthe material through channels or other cavities. Fabrics, particularlythose of sufficient heaviness, as well other types of usable materials,such as foams and sponges are generally porous. By “continuouslycavitated” is meant a material whose volume comprises interconnectedcavities which are continuous with the exterior of the material.Lattice-type structures (i.e., those having interconnected cavities ofregular shape and size) qualify as “continuously cavitated.”

The material creates a volume over which a vacuum can be maintained. Itscompressibility, even if only slight or incompletely reversible, such asin the case of most fabrics, enables the material, upon seeking toexpand its volume after compression, to aid in the creation of a vacuumin the space bounded by the interface, the suspension sleeve, and theprosthetic socket (the “interstitial volume”). Furthermore, uponambulation, the compressibility of the material enables a largerproportion of the air in the interstitial volume to be evacuated, eitherthrough one way valves, as discussed infra, or through the interfacesbetween the sleeve and the prosthesis or the sleeve and the proximalportion of the interface. Preferably, the material is a layer of fabricwith sufficient heaviness an compressibility that it can define a volumeover which a moderate vacuum in the range of from about 2 inches Hg toabout 14 inches Hg can be established upon ambulatory motion.

As indicated infra, the material is distributed over the distal portionof the interface, leaving a circumferentially continuous proximalportion free of material. In one embodiment, the entire proximal portionis characterized by a surface having the ability to seal with the innersurface of a selected suspension sleeve such that a moderate vacuum inthe range of from about 2 to 14 inches Hg is maintained for at least 30minutes of ambulatory activity, and more preferably for at least 60minutes of ambulatory activity. In another embodiment, at least acircumferentially continuous subportion of the aforementioned portion ischaracterized by a surface having the foregoing qualities.

It should be noted that the quality of the foregoing seal has adependence on the ability of the inner surface of the suspension sleeveto seal distally with the outer surface of the prosthetic at acircumferentially continuous region distal to the socket edge. Thequality of the foregoing seal also depends on the ability of thesuspension sleeve to seal proximally at a circumferentially continuousregion proximal to the material leading edge. By “circumferentiallycontinuous” is meant pertaining to an area which circumscribes. Thus, ingeneral, the suspension sleeve must be long enough to simultaneouslyengage in both seals. Furthermore, the suspension sleeve must have thecombination of physical dimensions such as unstretched and stretchedcircumferences and elastic dimensions such as elasticity, tensilestrength, deformability, and the like to in order to create efficientseals. This is considered to be within the purview of the prior art.Furthermore, the efficiency of the seal depends on the quality of thecontact between the suspension sleeve and the respective surfaces. In apreferred embodiment, the suspension sleeve comprises one material whichforms a seal which can sustain a moderate vacuum in the range of fromgreater than 2 inches Hg to about 14 inches Hg. In other embodiments,the sleeve comprises a material differential from one end to the otherend such that the overall efficiency of sealing the interstitial volumeis improved over the sealing efficiency of the material compositions ofthe respective ends. In another embodiment, the sleeve comprises regionsof two distinct materials which are joined together. In an additionalembodiment, the region of joining comprises horizontal overlap ofregions of the respective. By “horizontal” is meant parallel to thecylindrical axis. In yet another embodiment, an additional component isincluded to enhance the quality of the seal, and, optionally, is used toimprove the efficiency of the seal. Such a component can be an adhesivewhich is mild and temporary such that it improves the vacuum-holdingpower of the seal, yet allows the sleeve to be removed, undamaged by thewearer. In some instances, it may be convenient to use a band or othercircumferential securing mechanism to increase the efficiency of theseal. In other cases bio-sealants or other intermediate layers whichcontact the liner on one side and the suspension sleeve on the other maybe used. The purview of the present invention is considered to encompassmethods or additional measures for improving the vacuum-sustainingability of the seal, even if the seal in the absence of the method ormeasure does not exhibit the ability to maintain a vacuum in the rangeof from 2-14 inches with ambulation, as long as the seal in the presenceof the methods or measures does maintain such efficiency.

The Drawings

FIG. 1: An existing liner design showing the wearer's residual limb, afabric layer (2), an outer elastomeric layer (3) and a suspension sleeve(4) which make up the thigh seal.

FIG. 2 Close view of thigh seal illustrated in FIG. 1.

FIG. 3 A liner having an elastomeric layer (7) as well as a partialfabric overlay (6).

FIG. 4 A liner assembly showing the wearer's residual limb (8); theliner with an elastomeric layer (9) and partial overlying material layer(12); a prosthetic socket (10); and a suspension sleeve (9).

DETAILED DESCRIPTION OF THE DRAWINGS

Existing liner designs are as in FIG. 1. The liner includes a fabriclayer (2) into which a wearer's prosthetic limb (1) is inserted. Thelimb/liner combination is inserted into a prosthetic socket (3). Theprosthetic socket, against which the distal portion of a suspensionsleeve (4) can seal, overlies the distal portion of the fabric layer(5), extending proximally, to some extent, up the residual limb (1). Thesuspension sleeve, in its proper functioning position, extendsproximally from the socket, over the fabric liner, to the thigh of thepatient, against which a seal is formed. A vacuum is established in thevolume between the socket, the residual limb and the suspension sleeve.

FIG. 2 is a close view of the sealing function of the suspension sleeve(3), including he prosthetic socket(3), the fabric liner (5) and theresidual limb (1).

FIG. 3 is an illustration of the liner of the present inventioncomprising an elastomeric layer or interface layer (7), and a materiallayer (6) which overlies the distal end of the elastomeric layer. Thematerial layer comprises a leading edge (8). In different embodiments,the material layer can be unrecessed, partially recessed or fullyrecessed. Shown is a fully recessed leading edge, in which the materiallayer is sunken into the surface of the interface or elastomeric layer.An unrecessed leading edge may cause a discontinuity in the surface ofthe liner at the transition between the surfaces of the material layerand the interface layer. In another embodiment, the material layer isunrecessed, but the leading edge tapers such that the transition betweenthe surface of the material layer and the interface is continuous.Regardless of whether the transition is continuous or discontinuous, theliner of the present invention, when used properly with a suspensionsleeve, is generally able to form and sustain a moderate volume in theinterstitial area.

FIG. 4 is a depiction of the liner of the present invention as is itproperly involved in a liner assembly. The interface or elastomericlayer (9) has a residual limb (8) fittingly retained therein. The outersurface of the elastomeric layer is distally overlaid with a materiallayer (12) having a leading edge (13). A distal portion of thelimb-containing liner is fittingly received into a prosthetic socket(10), and a suspension sleeve (11) is sealingly applied such that itoverlies the prosthetic socket edge (14), sealing against a proximalportion of the socket, as well as a portion of the elastomeric layerwhich is more proximal than the socket edge.

1. A prosthetic device comprising an elastomeric liner comprising anopen end and a closed end; wherein the length of the elastomeric linerfrom open end to closed end is in the range of from 9 to 24 inches; andwherein the elastomeric liner has fabric bonded to the exterior from theclosed end for a distance in the range of from about 4 to 21 inchestoward the open end wherein said fabric does not reach said open end. 2.A prosthetic device comprising an elastomeric liner comprising an openend and a closed end; wherein the elastomeric liner is overlaid withfabric except for a circumferentially continuous area comprising theopen end.
 3. A prosthetic assembly comprising: a) a prosthetic liner asclaimed in claim 1 or 2; b) a residual limb contained by said liner; c)a prosthetic device comprising an external surface, a socket comprisingan internal surface and a socket edge, the liner-contained residual limbof 3(b) being inserted into said socket and contacting said internalsurface; and d) a suspension sleeve which is applied such that it formsa circumferential seal in at least two locations comprising 1) on theexternal surface of the prosthetic and 2) on the area of said liner towhich no fabric is bonded or overlaid.
 4. A prosthetic liner comprisingan elastomeric liner comprising an open end and a closed end; whereinthe open end has a perpendicular distance in the range of from 8 to 20inches from the closed end; and wherein the elastomeric liner isuniformly overlaid with a fabric or foam to a perpendicular distance inthe range of from about 4 to 16 inches from the open end. 5) Aprosthetic assembly comprising: a) a prosthetic liner comprising anelastomeric liner comprising a closed end and an open end and over laidwith foam or fabric except for a circumferentially continuous areacomprising the open end; b) a residual limb fittingly contained by theliner of 1); c) a prosthetic comprising a socket which the residual limbof 2 is inserted; and d) a suspension sleeve which is sealingly appliedsuch that it forms a circumferential seal in at least two placescomprising on the prosthetic surface and on the area of a); such thevolume bounded by elastomeric liner, the suspension sleeve and thesocket can sustain at least one vacuum in the range of from 2 to 14inches Hg.
 6. A prosthetic liner comprising: a) a distal closed end; b)a proximal open end comprising a proximal edge; c) an inner surface; d)an outer surface; e) an elastomeric interface layer; f) a porous orcontinuously cavitated compressible material layer; g) a materialleading edge; wherein said inner surface comprises said elastomericlayer; wherein said outer surface comprises said material layer and saidelastomeric layer, and wherein said material layer overlays saidelastomeric layer except for a circumferentially continuous region ofsaid outer surface comprising said proximal open end.
 7. A prostheticliner as in claim 6 wherein said porous or continuously cavitatedcompressible material layer comprises fabric.
 8. A prosthetic liner asin claim 6 wherein said polymer layer comprises one or more of thepolymer materials from the list consisting of the following types:polyurethane, polybutylene, polypropylene, and styrene block copolymers.9. A prosthetic liner as in claim 6 or 7 wherein said material layercomprises one or more of the fabric materials from the list consistingof: woven, nonwoven, synthetic and non-synthetic fabrics.
 10. Aprosthetic liner as in claim 1 wherein said material layer is presentexcept for the region having a perpendicular distance extending fromzero inches from said proximal edge to a distance in the range of fromabout 4 to about 15 inches from said proximal edge.
 11. A prostheticliner as in claim 6 wherein said material layer is recessed into saidpolymer layer.
 12. A prosthetic liner as in claim 11 wherein saidmaterial layer is recessed to a distance of about the thickness of thefabric layer.
 13. A prosthetic liner-socket assembly comprising: aprosthetic socket; a) a distal closed end; b) a proximal open endcomprising a proximal edge; c) an inner surface; d) an outer surface; e)an elastomeric interface layer; f) a porous or continuously cavitatedcompressible material layer; g) a material leading edge; h) a socket;wherein said inner surface comprises said polymer layer; wherein saidouter surface comprises said fabric layer and said polymer layer, andwherein said fabric layer overlays said polymer layer except for acontinuous region of said outer surface comprising said proximal openend and including said proximal edge; wherein the space occupied by thelayer of fabric is capable, when said liner and socket is donned by anamputee, of sustaining a negative pressure in the range of from aboveabout 2 inches Hg to about 14 inches Hg.
 14. A prosthetic liner as inclaim 13 wherein said porous or continuously cavitated compressiblelayer comprises fabric.
 15. A prosthetic liner as in claim 13 whereinsaid assembly additionally comprises a suspension sleeve.
 16. Aprosthetic liner as in claim 15 wherein said assembly is capable ofsustaining a negative pressure in the interstitial volume in the rangeof from about 5 to about 12 inches Hg.
 17. A prosthetic liner-socketassembly as in claim 13 wherein said polymer layer comprises one or moreof the polymer materials from the list consisting of the followingtypes: polyurethane, polybutylene, polypropylene, and styrene blockcopolymers.
 18. A prosthetic liner-socket assembly as in claim 16 or 17wherein said fabric layer comprises one or more of the fabric materialsfrom the list consisting of: woven, nonwoven, synthetic andnon-synthetic fabrics.
 19. A prosthetic liner-socket assembly as inclaim 13 wherein said fabric layer is present except for the regionhaving a perpendicular distance extending from zero inches from saidproximal edge to a distance in the range of from about 4 to about 15inches from said proximal edge.
 20. A prosthetic liner-socket assemblyas in claim 13 wherein said assembly further comprises a sheath, andwherein the space occupied by the layer of fabric is capable, when saidliner, socket and sheath is donned by an amputee, of sustaining anegative pressure in the interstitial region in the range of from aboveabout 0 to about 15 inches Hg.
 21. A prosthetic liner-socket assembly asin claim 20 wherein said fabric layer is recessed into said polymerlayer.
 22. A prosthetic liner-socket assembly as in claim 21 whereinsaid fabric layer is recessed to a distance of about the thickness ofthe fabric layer.